De Blasio won just over 40 percent of the vote in the Democratic mayoral primary last week and officially became the candidate after opponent Bill Thompson conceded on Sept. 16.

"Today, I’m proud to stand next to a great New Yorker and throw my support behind him," Thompson said in his own endorsement of de Blasio. "I am proud to stand here today and support Bill de Blasio to be the next mayor of the city of New York."

It showed de Blasio at 65 percent to 22 percent for Lhota among likely voters, including those undecided but leaning toward a candidate.

"It’s a very lopsided contest at this point," said Lee Miringoff, director of the Marist College Institute for Public Opinion. "Coming out of the starting blocks, it is playing de Blasio’s way in a big way."